1. Field of the Invention
This invention relates generally to molding, and more specifically to methods and apparatus for molding tires.
2. Description of the Related Art
In the construction of pneumatic tires, various uncured tire components are assembled together sequentially around a tire building drum and shaped around the drum into the desired toroidal form of the tire. The shaped uncured tire is then cured for strength and durability. Tire molds are used in the curing process to give a tire its final shape and appearance and to vulcanize the components of the tire.
Tire molds for curing complete tires are generally of two types: clamshell molds and segmented molds. Clamshell molds are two piece molds where half of the tire is molded in one half of the mold and the other half of the tire is molded in the other half of the mold. Segmented molds are a plurality of sector shaped segments that move radially as depicted in FIG. 1. With each type of mold, heated exterior components of the mold are moved into contact with the tread and sidewall portions of the uncured tire and cure the tire from the outside. A heated bladder is inflated or core contacts the inner surface of the tire to shape and cure the tire from the inside.
In segmented molds, a mold back is a wedge shaped component used to support the mold sectors that form the tread portions of the tire as shown in FIGS. 1 and 2. Sector tooling provides the connection between the mold back and the mold sector. The purpose of the sector tooling is to position the mold sectors circumferentially around the mold. Sector tooling is affixed to the mold back using several screws or bolts. The mold sector is then placed on the sector tooling by sliding the mold sector onto the sector tooling and securing with more screws or bolts. This connection between the sector tooling and the mold back and the sector tooling and the mold sector makes exchanging the tread pattern or changing the size of the tire labor intensive and time consuming. This type of sector tooling design does not allow for the sector tooling to be repositioned to accommodate changing the number of tread sectors. Therefore, the mold is dedicated to a particular tire size.